The problem is how to achieve the transformation as below:

The source xml contains tons of repeating structure like below, each
item
node contains a person element and a insurance element that correlate
to the
Person element with the person id.
<Item>
        <Person id="p123" name="someone1">
        <Insurance ref="p123" detail="blabla1">
</item>
<Item>
        <Person id="p123" name="someone1">
        <Insurance ref="p456" detail="blabla2">
</item>
<Item>
        <Person id="p456" name="someone1">
        <Insurance ref="p123" detail="blabla3">
</item>
The goal is to regroup to a structure of 1(Person) to many(Insurance),
like
below
<Item>
        <Person id="p123" name="someone1">
        <Insurance ref="p123" detail="blabla1">
        <Insurance ref="p123" detail="blabla3">
</Item>
My initial idea was to load the source into memory and dissect into
Hashtables so that I could easily regroup. However, since the source
file is
really big (approximate 50M each with 70000 repeating items), obviously
my
way of doing it is too memory consuming. I am frustrated, after a whole
day
sitting quietly and cannot figure out a better way, I would really
appreciate 
any help. 


Thanks in advance